Numerous apparatus have been developed for transdermal delivery of medicines using microneedle assemblies. Microneedle assemblies facilitate reducing an amount of pain felt by a patient as compared to larger conventional needles. Moreover, conventional subcutaneous (and often intra-muscular) delivery of medicines using a needle operates to deliver a large quantity of the medicine at one time, thereby creating a spike in the bioavailability of the medicine. While this is not a significant problem for some medicines, many medicines benefit from having a steady state concentration in the patient's blood stream. Transdermal delivery apparatus are capable of administering drugs at a substantially constant rate over an extended period of time.
However, delivery of medicine using transdermal delivery apparatuses poses several challenges. For example, with at least some known transdermal delivery apparatuses, the placement of the device with respect to a user's skin and the amount of force used to attach the device to the skin can vary, thereby affecting the ability of the microneedles to properly penetrate the user's skin. In addition, the medicine may have air bubbles dispersed therethrough, which can also affect the delivery of the medicine through each microneedle of the microneedle assembly. Moreover, the quantity of the medicine delivered through each microneedle of the microneedle assembly may not be constant or equal due to variances in the pressure supplied to the medicine.